Hall-effect controller

Abstract

A Hall-effect control apparatus incorporating an actuator member having a magnetic core, and which is pivotally mounted on a base for movement in X-axis and Y-axis directions. An electrically energized coil excited with a. c. voltage produces a fluctuating magnetic field in the vicinity of the core. Four Hall-effect sensors are mounted on the base, and are arranged to sense changes in the a. c. field as the core member moves. The output of the Hall-effect sensors is both d. c. and a. c.; an electrical circuit connected therewith processes these voltages so as to cancel out any d. c. components thereof. The output of the electrical circuit in turn provides two voltages which are indicative of the X-axis and the Y-axis positions of the actuator member. The device is immune to interruption arising from d. c. fields, such as that of the earth; also significant immunity against error due to temperature fluctuations is realizeable, as is immunity to error arising from aging of the various components. There is thus achieved improved accuracy and linearity as compared to the various devices of the prior art.

What is claimed is: 
     
       1. A joystick control, comprising in combination: (a) a base,   (b) a movable actuator member,   (c) means pivotally mounting the actuator member for tilting movement on the base,   (d) means providing a fluctuating electric field on the base,   (e) said actuator member carrying a magnetic core movable with respect to said fluctuating electric field providing means, thereby to alter the said fluctuating electric field as the actuator member is moved,   (f) a Hall-effect sensor rigid with respect to the base and disposed so as to be under the influence of said fluctuating electric field,   (g) said Hall-effect sensor providing a fluctuating electrical output signal in response to fluctuations of said fluctuating electric field, and   (h) electronic circuit means connected to said Hall-effect sensor, for converting the fluctuating output signal thereof to essentially a d.c. voltage which varies with changes in the position of the magnetic core carried by said actuator member.   
     
     
       2. A joystick control, comprising in combination: (a) a base,   (b) a movable actuator member,   (c) means pivotally mounting the actuator means for tilting movement on the base,   (d) means providing a fluctuating electric field on the base,   (e) said actuator member having a magnetic core movable with respect to said fluctuating electric field providing means, thereby to alter the fluctuating electric field as the actuator member is moved,   (f) a pair of Hall-effect sensors rigid with respect to the base and providing a pair of fluctuating electrical output signals in response to fluctuations of said electric field,   (g) electronic circuit means connected to said Hall-effect sensors, for blocking the d.c. component of the output signals therefrom, and for passing at least a portion of the a.c. components thereof, and   (h) means for converting the a.c. components of the output signals of said Hall-effect sensors to d.c. voltages, whereby said d.c. voltages vary with changes in the position of the magnetic core with respect to said Hall-effect sensors.   
     
     
       3. The invention as set forth in claim 2, and further including: (a) an additional pair of Hall-effect sensors, said first-mentioned pair being circumferentially disposed essentially 180° apart from one another,   (b) said additional pair of Hall-effect sensors being circumferentially disposed essentially 180° apart from one another, and 90° from said first pair of Hall-effect sensors.   
     
     
       4. The invention as set forth in claim 2, wherein: (a) said electronic circuit means comprises a series coupling capacitor which blocks d.c. voltage, and   (b) said converting means comprising an amplifier and peak detector circuit, connected with said coupling capacitor, responsive to the peaks of the a.c. component of the signal passing through said coupling capacitor, said peak detector circuit providing an essentially d.c. signal at its output.   
     
     
       5. The invention as set forth in claim 4, wherein: (a) said peak detector circuit comprises an analog switch, and   (b) a capacitor connected to the output of the analog switch, said capacitor being capable of being charged by the output of said analog switch, and holding the said charge.   
     
     
       6. The invention as set forth in claim 2, wherein: (a) said means for providing a fluctuating electric field on the base comprises an electrical inductor, and   (b) a signal generator, connected with said inductor and adapted to provide a fluctuating flux therearound.   
     
     
       7. The invention as set forth in claim 6, wherein: (a) said signal generator comprises a pulse generator.   
     
     
       8. The invention as set forth in claim 2, wherein: (a) said electronic circuit means comprises an analog switch,   (b) means connecting the input of the analog switch to the output of one of said Hall-effect sensors,   (c) said means providing a fluctuating electric field comprising a pulse generator, and   (d) means interposed between said pulse generator and said analog switch, to trigger the latter into conduction in phase with the outputs from said Hall-effect sensors.   
     
     
       9. A joystick control, comprising in combination: (a) an electrical coil and exciting means therefor, for producing a fluctuating magnetic field,   (b) a Hall-effect sensor adjacent said coil,   (c) a magnetic core for altering the fluctuating magnetic field sensed by the Hall-effect sensor,   (d) said magnetic core and coil being movable with respect to one another, and   (e) electronic circuit means connected with said Hall-effect sensor, for converting the output of the sensor to an essentially d.c. voltage which varies with the relative positions of the core and coil.   
     
     
       10. A control apparatus, comprising in combination: (a) means for producing a fluctuating magnetic field,   (b) magnetic detector means under the influence of said field-producing means, said magnetic detector means having an output wave corresponding to the strength of said magnetic field,   (c) switching means connected with said field-producing means and said detector means, and   (d) means for triggering said switching means into conduction at a predetermined point in the phase of each cycle in the output wave of the magnetic detector means,   (e) said switching means providing a d.c. voltage which can be correlated to the magnitude of the said output wave at the said predetermined point.   
     
     
       11. A joystick control, comprising in combination: (a) a pivotal magnetic member having a fluctuating flux,   (b) a Hall-effect sensor adjacent said member and influenced by the flux thereof,   (c) connecting circuitry including a blocking capacitor connected to said Hall-effect sensor, producing from the signal thereof a fluctuating wave,   (d) electronic switching means connected to said connecting circuitry,   (e) an output circuit, and   (f) means synchronized with the flux of the magnetic member, controlling said switching means to drive said output circuit with the fluctuating wave from the connecting circuitry.